The Design and Mechanical Performance Characteristics of the Zero Power Plutonium Reactor

Abstract

The Zero Power Plutonium Reactor (ZPPR) is a fast experimental reactor that operates at very low power levels and is used to simulate proposed fast power plutonium reactors in the 1000-MW range. The reactor is built on two large tables, one stationary and one movable, with numerous roller bearings on the underside for ease of travel. Half of the reactor is built on each table, and then the tables are brought together before the reactor can go critical. The tables are each designed to support at least 120 tons of fuel and structural material. Load tests were conducted to prove the system and to determine deflections in the foundation and runways. Many safety devices are built into the table drive system, such as an electric feed-rail system that disconnects the power supply to the drive motor if a relay fails, three speeds of table closing to control reactivity-addition rates, and two independent table-separation systems. Fuel control rods are used for reactivity changes; fuel and poison safety rods are used for shutdown control. Core material is loaded into 2 × 2 × 23-in. drawers, and the drawers are slid into matrix tubes stacked 10 feet high on the tables. Matrix tubes and drawers and the tables were aligned to obtain a minimum gap at the interface.